#include "my_stdio.h"

#include<string.h>
#include<stdlib.h>
#include<sys/stat.h>
#include<sys/types.h>
#include<fcntl.h>
#include<unistd.h>


mFILE* mfopen(const char* filename,const char* mode)
{
    int fd = -1;
    if(strcmp(mode,"r") == 0)
    {
        fd = open(filename,O_RDONLY);
    }
    else if(strcmp(mode,"w") == 0)
    {
        fd = open(filename,O_CREAT | O_WRONLY | O_TRUNC,0666);
    }
    else if(strcmp(mode,"a") == 0)
    {
        fd = open(filename,O_CREAT | O_WRONLY | O_APPEND,0666);
    }

    if(fd < 0) return NULL;

    mFILE* mf = (mFILE*)malloc(sizeof(mFILE));
    if(!mf)
    {
        close(fd);
        return NULL;
    }
    
    mf->fileno = fd;
    mf->flag = FLUSH_LINE;
    mf->size = 0;
    mf->cap = SIZE;

    return mf;
}

void mfflush(mFILE* stream)
{
    if(stream->size > 0)
    {
        // 写到内核文件的文件缓冲区中
        write(stream->fileno,stream->outbuffer,stream->size);
        // 刷新到外设
        fsync(stream->fileno);
        stream->size = 0;
    }
}
int mfwrite(const void* ptr,int num,mFILE* stream)
{
    // 1.拷贝
    memcpy(stream->outbuffer + stream->size,ptr,num);
    stream->size += num;

    // 2.检测是否要刷新
    if(stream->flag == FLUSH_LINE && stream->size > 0 && stream->outbuffer[stream->size-1] == '\n')
    {
        mfflush(stream);
    }
    return num;
}

void mfclose(mFILE* stream)
{
    if(stream->size > 0)
    {
        mfflush(stream);
    }
    close(stream->fileno);
}
